Effects of detergents and organic solvents on rat liver microsomal UDP-glucuronosyltransferase activity towards phenolic substrates.
1. The effects of several detergents (Brij 58, deoxycholate and Lubrol 12A9) and ether on the initial rate of UDP-glucuronosyltransferase activity towards fixed concentrations of five phenolic acceptor substrates of widely different octanol-buffer (pH 7.4) partition coefficient have been compared with those observed in non-activated and Triton X-100-and n-pentane-activated rat liver microsomes. 2. Enzymic activity was dependent on the lipid-solubility of acceptor substrate. Each activator, except Triton X-100, enhanced enzymic activity towards all substrates by a similar factor, which was independent of the octanol-buffer partition coefficient. For Triton X-100 microsomes, the activation was also partition-dependent. 3. The highest activation factor was seen with ether. Pre-incubation of ether-activated microsomes for 30 min at 37 degrees C before assay resulted in inactivation of the enzyme towards more water-soluble substrates. Tryptic digestion (30 min at 37 degrees C) of the ether-activated microsomes resulted in marked reduction of enzyme activity towards all substrates. 4. Ether, and the two detergents, Brij 58 and Lubrol 12A9, released small amounts of protein (5-12% total present); both detergents also released some (8-12%) phospholipid. 5. The Kappm towards acceptor substrate also depended on the octanol-buffer partition coefficient, and was largely unchanged on activation by n-pentane. Vmax was not dependent on partition coefficient and was significantly increased on activation.
D000818:Animals; D002592:Cetomacrogol / Q000494:pharmacology; D003840:Deoxycholic Acid / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology*; D004986:Ether / Q000494:pharmacology; D014453:Glucuronosyltransferase / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D017830:Octoxynol; D010420:Pentanes / Q000494:pharmacology; D010636:Phenols / Q000378:metabolism*; D000077423:Polidocanol; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012997:Solvents / Q000494:pharmacology*; D013501:Surface-Active Agents / Q000494:pharmacology*
D003902:Detergents; D010420:Pentanes; D010636:Phenols; D012997:Solvents; D013501:Surface-Active Agents; D003840:Deoxycholic Acid; D000077423:Polidocanol; D004986:Ether; D011092:Polyethylene Glycols; C033353:pentane; D017830:Octoxynol; D002592:Cetomacrogol; D014453:Glucuronosyltransferase